A long time back, most of the software used to ship with .hlp (WinHelp help format) help files. Since Windows Vista, the legacy .hlp format has been deprecated. To view 32-bit Help files with the .hlp file extension in Windows Vista (and higher — through Windows 8.1), you will need to download and install WinHlp32.exe (KB917607 package) from the Microsoft Download Center.However, this update isn’t available for Windows 10. This article tells you how to restore the missing WinHelp (.hlp) viewer in Windows 10.